Introduction
The surface finishing of stainless steel pipes varies depending on the environmental conditions. Understanding the impact of the environment on stainless steel pipes is crucial in selecting the appropriate type of stainless steel pipes, as failure to do so can result in rusting and corrosion. Different types of
stainless steel pipes require different surface treatments, including:
Acid pickling or sandblasting finish for industrial-grade seamless stainless steel pipes.
Polished surface for seamless sanitary stainless steel pipes.
Polished surface for small-diameter stainless steel welded pipes.
Acid pickling or sandblasting treatment for industrial-grade stainless steel welded pipes.
Internal and external polishing for sanitary welded stainless steel pipes.
Pre-Treatment
Pre-treatment processes play a vital role in the surface treatment of stainless steel pipes. These processes include pickling, chemical brightening, electrochemical polishing, electroplating, passivation, black coating, color coating, and chemical processing. Before the formation of stainless steel pipes, the surface may contain oil, burrs, unevenness, and oxides. Therefore, it is essential to remove these defects before undertaking surface treatment.
The dirt to be removed from the surface of stainless steel pipes can be categorized into organic and inorganic substances. Organic substances comprise mineral oils such as diesel, engine oil, vaseline, paraffin, animal oils, and vegetable oils like soybean oil, camellia oil, rapeseed oil, lard, and tallow. Oil contamination typically results from lubricating oil, cutting oil, quenching oil, polishing oil, or fingerprints generated during the processing of stainless steel pipes. Inorganic substances include soil, dust, compounds, and other residues resulting from the heat treatment process.
Stainless Steel Pipe Pre-Treatment Procedure
(1) Polishing: Eliminate surface roughness of stainless steel by mechanically grinding and polishing it to achieve a desired level of surface smoothness.
(2) Degreasing: Remove surface oil contamination.
(3) Pickling: Eliminate surface oxides.
(4) Weak Corrosion: Activate the surface to be treated, remove the passive film, and expose the metal crystal structure.
Surface Treatment Methods for Stainless Steel Pipes:
(1) Mechanical Methods: Employ polishing machines or other machinery to remove surface roughness.
(2) Chemical Methods: Employ alkaline solutions for degreasing, acidic solutions for pickling, and organic solvents for oil and scale removal.
(3) Electrochemical Processes: Utilize electrochemical methods to remove oil and perform electrochemical etching.
(4) Buffing, centrifugal buffing, centrifugal disk polishing, rotational polishing, suitable for small parts that require flattening and rust removal effects.
(5) Sandblasting Treatment: Suitable for large-area treatment, providing cleaning and oxide scale removal effects.
Therefore, the appropriate method should be selected based on the surface condition of the stainless steel pipe and the subsequent quality requirements.
